Parentage: ‘GRAosr’ is a seedling selection which resulted from the controlled cross-pollination of an unnamed Rosa hybrid female breeding line and an unnamed Rosa hybrid male breeding line. Both parents, developed by the same inventor and never commercially released, exhibited traits deemed commercially significant and desirable.
After many years of trialing, the female parent was confirmed to possess a combination of desirable traits such as very strong fragrance and having flower color white, borne on a bushy plant growing to 1.2 m tall and wide. The male parent was selected for use in breeding after trialing confirmed the presence of a modern flower color. During the spring of 2014, the female parent was emasculated and was manually pollinated with pollen from the male parent. In autumn of 2015, seed was collected from hips produced by the female parent and a number of seedlings were grown to a mature size, including the claimed plant. These progeny were further evaluated for desirable traits such as black spot disease resistance and original flower color, and in January of 2016 the claimed plant was first observed. In January of 2017, after further evaluation for desirable traits, the claimed plant was deemed to be garden-worthy and suited to widespread cultivation. It was given the denomination ‘GRAosr’.
Asexual Reproduction: Asexual propagation of ‘GRAosr’, by way of softwood stem cuttings, was first performed in May of 2016 at the inventor's nursery in Highfields, Australia. Through more than twelve subsequent generations, the unique features of this cultivar have proven to be stable and true to type.